The sintered anodes of solid electrolytic capacitors consist of a valve metal, tantalum being principally employed. There are, however, other valve metals, such as zircon or niobium, for examples, which are used in solid electrolytic capacitors. The semi-conducting electrolyte generally employed is a manganese dioxide coating which is applied by dipping the sintered body in a manganese nitrate bath followed by subsequent pyrolysis of this coating. This procedural sequence is generally repeated a few times for a given body. It is also possible to use other semi-conducting metal oxides, such as lead dioxide, for example, as an electrolyte. A thin oxide coating of the valve metal, which is produced on the valve metal in a forming process, serves as a dielectric layer in solid electrolytic capacitors. Forming electrolytes are employed for the forming process, a voltage being applied to the sintered body, so that an anodic oxidation of the valve metal is effected.
In the application of the semi-conducting electrolyte, and also of the cathode contact layer (generally a graphite coating with a layer of conducting silver enamel thereon), it is possible for the oxide layer acting as dielectric layer to be destroyed at some points. Consequently, in order to achieve stable electrical values for solid electrolytic capacitors, such capacitors are reformed in the final phase of their manufacture. In reforming, such capacitors are subjected to a voltage across an individual barrier resistance for a relatively long period of time (about 1 day) at an elevated temperature (about 85.degree. to 125.degree. C). This reforming method is, however, very expensive, since a barrier resistance is needed for each individual capacitor. Moreover, the contact elements are subjected to a high stress at temperatures ranging from about 85.degree. to 125.degree. C which are necessary for the forming and aging. Also, in order to ensure satisfactory contacting, contact elements must be serviced or exchanged at short intervals with a high resultant cost.